Self-pivoting spinal implant and associated instrumentation

ABSTRACT

An intervertebral implant includes an insertion end, an opposing engagement end, and first and second opposed main surfaces configured to contact respective adjacent vertebral endplates. Each of the first and second main surfaces has an anterior edge, a posterior edge, and extends between the insertion and engagement ends. Anterior and posterior walls are formed between the first and second main surfaces and along the respective anterior and posterior edges and converge at the insertion and engagement ends. A slot is formed at the engagement end and extends continuously between and at least partially along the anterior and posterior walls. A post is positioned within the slot, spaced from at least one of the anterior and posterior walls and extending at least partially between the first and second main surfaces. The post includes a plurality of exposed facets and is configured for engagement with a pivotable insertion instrument.

BACKGROUND OF THE INVENTION

The unilateral transforaminal insertion of an interbody spacer forlumbar spinal fusion presents challenges to the surgeon tasked with theprocedure due to the curved manipulation path that the implant mustundergo once it enters the disc space. The procedure presents a furtherchallenge of coupling the implant to the inserter instrument whileallowing the implant a limited amount of rotation or articulation tofollow the desired path. These challenges also present themselves toother angular unilateral approaches to the spine, in which the initialaccess corridor is linear yet, once the implant enters the disc space,the implant must be manipulated or articulated along a curved path.Conventional transforaminal lateral interbody fusion (TLIF) implants,for example, are inserted using a combination of a linear insertion pathand a hammering of the implant into the desired position using pushersthat provide the desired anterior positioning of the implant.Alternately, a stepwise straight hammering process alternating with anactive turning technique is often used to manipulate the implant fromthe entry position to the final desired position. The conventional TLIFand other angular unilateral systems and insertion methods fail toprovide implants, instrumentation, and methods that allow the implant tobe easily inserted to its final desired position within the disc space.

It is therefore desired to provide a spinal implant and associatedinstrument and method that improves the ease with which the implant maybe manipulated during insertion or once within the disc space.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, a first embodiment of the present invention comprises anintervertebral implant including an insertion end, an opposingengagement end, and first and second opposed main surfaces configured tocontact respective adjacent vertebral endplates. Each of the first andsecond main surfaces has an anterior edge, a posterior edge, and extendsbetween the insertion and engagement ends. An anterior wall is formedbetween the first and second main surfaces and along the anterior edgesthereof. A posterior wall is formed between the first and second mainsurfaces and along the posterior edges thereof. The anterior wall andthe posterior wall converge at the insertion and engagement ends. A slotis formed at the engagement end and extends continuously between and atleast partially along the anterior and posterior walls. A post ispositioned within the slot, spaced from at least one of the anterior andposterior walls and extending at least partially between the first andsecond main surfaces. The post includes a plurality of exposed facetsand is configured for engagement with a pivotable insertion instrument.

Another embodiment of the present invention comprises an intervertebralimplant including an insertion end, an opposing engagement end, andfirst and second opposed main surfaces configured to contact respectiveadjacent vertebral endplates. Each of the first and second main surfaceshas an anterior edge, a posterior edge, and extends between theinsertion and engagement ends. Each anterior edge has a generally linearportion proximate the engagement end and a generally concave portion,and each posterior edge has a generally linear portion proximate theengagement end and a generally convex portion. The generally linearportion of the anterior edge converges with the generally linear portionof the posterior edge at the engagement end for each of the first andsecond main surfaces. An anterior wall is formed between the first andsecond main surfaces and along the anterior edges thereof. A posteriorwall is formed between the first and second main surfaces and along theposterior edges thereof. The anterior wall and the posterior wallconverge at the insertion and engagement ends. A slot is formed at theengagement end and extends continuously between and at least partiallyalong the anterior and posterior walls. A post is positioned within theslot, spaced from at least one of the anterior and posterior walls andextending at least partially between the first and second main surfaces.The post includes a plurality of exposed facets and is configured forengagement with a pivotable insertion instrument.

Still another embodiment of the present invention comprises anintervertebral implant including an insertion end, an opposingengagement end, and first and second opposed main surfaces configured tocontact respective adjacent vertebral endplates. Each of the first andsecond main surfaces has an anterior edge, a posterior edge, and extendsbetween the insertion and engagement ends. Each anterior edge isgenerally concave and each posterior edge is generally convex. Ananterior wall is formed between the first and second main surfaces andalong the anterior edges thereof. A posterior wall is formed between thefirst and second main surfaces and along the posterior edges thereof.The anterior wall and the posterior wall converge at the insertion andengagement ends. A slot is formed at the engagement end and extendscontinuously between and at least partially along the anterior andposterior walls. A post is positioned within the slot, spaced from theanterior and posterior walls and extending at least partially betweenthe first and second main surfaces. The post includes a plurality offacets disposed around an entire periphery thereof and is configured forengagement with a pivotable insertion instrument. At least one abutmentsurface is disposed within the slot distally from the post. The at leastone abutment surface limits rotation of the implant about the post whenthe post is engaged with the pivotable insertion instrument.

Yet another embodiment of the present invention comprises anintervertebral implant including an insertion end, an opposingengagement end, and first and second opposed main surfaces configured tocontact respective adjacent vertebral endplates. Each of the first andsecond main surfaces has an anterior edge, a posterior edge, and extendsbetween the insertion and engagement ends. Each anterior edge isgenerally concave and each posterior edge is generally convex. An axialbore is formed between the anterior and posterior edges and extendsbetween the first and second main surfaces. An anterior wall is formedbetween the first and second main surfaces and along the anterior edgesthereof. A posterior wall is formed between the first and second mainsurfaces and along the posterior edges thereof. The anterior wall andthe posterior wall converge at the insertion and engagement ends. A slotis formed at the engagement end and extends at least partially along theanterior and posterior walls. A post is positioned within the slot andextends at least partially between the first and second main surfaces.The post includes a plurality of facets and is configured for engagementwith a pivotable insertion instrument. The intervertebral implant alsoincludes a plurality of markers. At least one of the markers extendsbetween the first and second main surfaces within one of the anteriorand posterior walls. At least one other of the markers is disposedgenerally transverse to the at least one of the markers and extends fromthe insertion end toward the axial bore.

A still further embodiment of the present invention comprises a methodfor implanting an intervertebral implant into a disc space disposedbetween first and second endplates of adjacent vertebral bodies of apatient. The method includes providing an access corridor to a spinallevel in need, removing at least a portion of disc material between theadjacent vertebra, and providing an interbody spacer implant. Theimplant includes an insertion end, an opposing engagement end, and firstand second opposed main surfaces configured to contact the respectivefirst and second vertebral endplates. Each of the first and second mainsurfaces has an anterior edge, a posterior edge, and extends between theinsertion and engagement ends. Each anterior edge is generally concaveand each posterior edge is generally convex. Each of the first andsecond main surfaces includes a plurality of curved parallel ridgesprotruding from the respective surface and extending from the insertionend to the engagement end. Each of the plurality of parallel ridgesincludes a plurality of teeth. An anterior wall is formed between thefirst and second main surfaces and along the anterior edges thereof. Aposterior wall is formed between the first and second main surfaces andalong the posterior edges thereof. The anterior wall and the posteriorwall converge at the insertion and engagement ends. A slot is formed atthe engagement end and extends continuously between and at leastpartially along the anterior and posterior walls. A post is positionedwithin the slot, spaced from at least one of the anterior and posteriorwalls and extending at least partially between the first and second mainsurfaces. The post includes a plurality of exposed facets and isconfigured for engagement with a pivotable insertion instrument. Themethod also includes providing an insertion instrument. The instrumentincludes a proximal end, a distal end, and a longitudinal axistherebetween, and an inner member and an outer member. The inner memberis movable along the longitudinal axis with respect to the outer member.The inner member has a grasping portion at the distal end. The graspingportion includes a plurality of facet surfaces configured for engagementwith the plurality of the post facets. The method also includesinserting the grasping portion of the instrument into the slot of theimplant such that the grasping portion surrounds the post, engaging thepost of the implant with the grasping portion of the instrument suchthat the post is rotationally fixed with respect to the graspingportion, inserting the implant using the instrument through the accesscorridor until at least the insertion end is introduced into the atleast partially cleared out disc space and such that the at least aportion of the ridges of the first and second main surfaces contact thefirst and second verebtral endplates, respectively, adjusting theinstrument such that the post of the implant remains engaged with thegrasping portion of the instrument but rotation of the post is permittedwithin the grasping portion, delivering impaction forces to the proximalend of the instrument such that the post of the implant articulates withrespect to the grasping portion of the instrument and the implant isguided by vertebral rails into a desired position, releasing the post ofthe implant from the grasping portion of the instrument, and withdrawingthe instrument through the access corridor.

Yet another embodiment of the present invention comprises a system forspine surgery at a disc space disposed between first and secondendplates of adjacent vertebral bodies of a patient. The system includesan intervertebral implant including an insertion end and an opposingengagement end. First and second opposed main surfaces are configured tocontact respective adjacent vertebral endplates. Each of the first andsecond main surfaces has an anterior edge, a posterior edge, and extendsbetween the insertion and engagement ends. An anterior wall is formedbetween the first and second main surfaces and along the anterior edgesthereof. A posterior wall is formed between the first and second mainsurfaces and along the posterior edges thereof. The anterior wall andthe posterior wall converge at the insertion and engagement ends. A slotis formed at the engagement end and extends continuously between and atleast partially along the anterior and posterior walls. A post ispositioned within the slot, spaced from at least one of the anterior andposterior walls and extending at least partially between the first andsecond main surfaces. The post includes a plurality of exposed facets. Atrial implant includes an insertion end and an opposing engagement end.First and second opposed main surfaces are configured to contactrespective adjacent vertebral endplates. Each of the first and secondmain surfaces has an anterior edge, a posterior edge, and extendsbetween the insertion and engagement ends. An anterior wall is formedbetween the first and second main surfaces and along the anterior edgesthereof. A posterior wall is formed between the first and second mainsurfaces and along the posterior edges thereof. The anterior wall andthe posterior wall converge at the insertion and engagement ends. A slotis formed at the engagement end and extends continuously between and atleast partially along the anterior and posterior walls. A post ispositioned within the slot, spaced from at least one of the anterior andposterior walls and extending at least partially between the first andsecond main surfaces. The post includes a plurality of exposed facets.An insertion instrument includes a proximal end, a distal end, alongitudinal axis therebetween, an inner member, and an outer member.The inner member is translatable with respect to the outer member alongthe longitudinal axis and has a grasping portion at the distal end. Thegrasping portion includes a plurality of facet surfaces engagable withthe plurality of the post facets of the intervertebral implant and thetrial implant. The instrument has a first configuration in which thegrasping portion assumes an open configuration for allowing coupling ofthe instrument to the post of one of the intervertebral implant and thetrial implant, a second configuration in which the instrument issecurely coupled to the post of one of the intervertebral implant andthe trial implant while allowing the post to rotate within the graspingportion under a given force, and a third configuration wherein theinstrument is securely coupled to the post of one of the intervertebralimplant and the trial implant while preventing rotation of the post withrespect to the grasping portion.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofpreferred embodiments of the instrument of the present application, willbe better understood when read in conjunction with the appendeddrawings. For the purposes of illustrating the self-pivoting spinalimplant and the associated instrumentation of the present application,there is shown in the drawings preferred embodiments. It should beunderstood, however, that the application is not limited to the precisearrangements and instrumentalities shown. In the drawings:

FIG. 1 is a rear perspective view of a self-pivoting TLIF implant inaccordance with a first preferred embodiment of the present invention;

FIG. 2 is a front perspective view of the self-pivoting TLIF implant ofFIG. 1;

FIG. 3 is a top plan view of the self-pivoting TLIF implant of FIG. 1;

FIG. 4 is a front and left side perspective view of the self-pivotingTLIF implant of FIG. 1;

FIG. 5 is a front perspective view of the self-pivoting TLIF implant ofFIG. 1 and a bone growth promoting material configured for insertioninto the implant;

FIG. 6 is a front perspective view of the self-pivoting TLIF implant ofFIG. 1 showing a preferred arrangement of radiopaque markers;

FIG. 7 is a partial front perspective cross-sectional view of aninserter instrument in accordance with a first preferred embodiment ofthe present invention, the inserter instrument shown in openconfiguration;

FIG. 8A is a top plan view of the inserter instrument of FIG. 7;

FIG. 8B is a partial front perspective view of the inserter instrumentof FIG. 7 in the open configuration;

FIG. 9A is a top plan view of the inserter instrument of FIG. 7 in aninitial articulation position and in a finally locked configuration;

FIG. 9B is a cross-sectional view of the inserter instrument of FIG. 7in the initial articulation position and in the finally lockedconfiguration;

FIG. 9C is a cross-sectional view of the inserter instrument of FIG. 7in the initial articulation position and in a provisionally lockedconfiguration;

FIG. 9D is a cross-sectional view of the inserter instrument of FIG. 7in a final articulation position and in the provisionally lockedconfiguration;

FIG. 10A is a cross-sectional view of the inserter instrument of FIG. 7in the final articulation position and in the finally lockedconfiguration;

FIG. 10B is a top plan view of the inserter instrument of FIG. 7 in thefinal articulation position and in the finally locked configuration;

FIG. 10C is a cross-sectional view of the inserter instrument of FIG. 7in the final articulation position and in the open configuration;

FIG. 11A is a top plan view, partially broken away, of one position ofthe implant of FIG. 1 and the instrument of FIG. 7 with respect to adisc space, partially broken away, as the implant is inserted therein;

FIG. 11B is a top plan view, partially broken away, of a the implant andinstrument of FIG. 11A in a second position;

FIG. 11C is a top plan view, partially broken away, of a the implant andinstrument of FIG. 11B in a third position;

FIG. 11D is a top plan view of a the implant and instrument of FIG. 11Cin a fourth position;

FIG. 12A is a rear perspective view of a trial implant in accordancewith one embodiment of the present invention;

FIG. 12B front perspective view of the trial implant of FIG. 12A;

FIG. 12C is a rear elevational view of the trial implant of FIG. 12A;and

FIG. 12D is a left side elevational view of the trial implant of FIG.12A.

DETAILED DESCRIPTION OF THE INVENTION

Certain terminology is used in the following description for convenienceonly and is not limiting. The words “right,” “left,” “lower,” and“upper” designate directions in the drawings to which reference is made.The words “inwardly” or “distally” and “outwardly” or “proximally” referto directions toward and away from, respectively, the patient's body, orthe geometric center of the interbody spacer implant and related partsthereof. The words, “anterior,” “posterior,” “superior,” “inferior,” andrelated words and/or phrases designate preferred positions andorientations in the human body to which reference is made and are notmeant to be limiting. The terminology includes the above-listed words,derivatives thereof and words of similar import.

Referring to FIGS. 1-6, a TLIF spacer 100 is provided that includes aninsertion end 110 and an engagement end 115, the insertion end 110preferably forming a bullet-nose 112 or having some other taperedgeometry for enhancing the ease of insertion and/or for applying adistraction force to the two vertebral bodies between which the implant100 is configured to be inserted. The implant 100 further includes afirst main or superior surface 120 that is configured for contacting theinferior endplate of a superior vertebral body and a second main orinferior surface 125 that is configured for contacting the superiorendplate of an inferior vertebral body. One or more walls 130 onanterior and posterior sides extend between the superior and inferiorsurfaces 120, 125 and enclose an axial bore 140 that extends throughboth the superior and inferior surfaces 120, 125. The axial bore 140 isconfigured to house a bone graft 190 or other fusion enhancing material.

One or more lateral windows 150 are disposed in the walls 130 andprovide a visibility window for observing the fusion occurring betweenthe vertebral bodies and enhancing the vascularization of the bone graft190 disposed within the axial bore 140 to assist fusion, as well as toincrease the volume of the axial bore 140. One or more surface features145 are provided along interior portions of the walls 130 that form theaxial bore 140 to assist in securing the bone graft 190 within the axialbore 140. The features 145 can assume the form of one or more ridgesextending through the axial bore 140 along the cranial-caudal direction,grooves, or other surface texturing that enhances the friction betweenthe bone graft 190 and the interior of the walls 130 that form the axialbore 140.

In a first preferred embodiment, the TLIF spacer 100 has a kidney beanor banana shape having a curvilinear geometry between its insertion andengagement ends 110, 115. This shape may be accomplished by having ananterior edge of the superior and inferior surfaces 120, 125 along withthe anterior wall 130 be generally concave and a posterior edge of thesuperior and inferior surfaces 120, 125 along with the posterior wall130 be generally convex. However, a variety of geometries may beutilized for the implant 100, depending on the desired amount of surfacecontact between the endplates of the vertebral bodies and the implant100, the number of implants 100 desired to be implanted within the discspace (e.g., one or two), the approach chosen for the surgery, thedesired location of the implant within the disc space (anterior orposterior), or the like. Disposed upon the superior surface 120 adjacentthe insertion end 110 are a plurality of curvilinear superior ridges 160that are arranged parallel to one another along the curvature of theTLIF implant 100.

In a first preferred embodiment, the superior ridges 160 include twolinearly sloped surfaces that meet to form an apex. As the superiorridges 160 extend along their curvilinear path away from the insertionend 110, the superior ridges 160 are interrupted to form a plurality ofsuperior teeth 162. The superior teeth 162 are disposed at theengagement end 115 and along at least a portion of anterior andposterior sides of the axial bore 140. Similarly, disposed upon theinferior surface 125 adjacent the insertion end 110 is a plurality ofcurvilinear inferior ridges 165 that are arranged parallel to oneanother along the curvature of the TLIF implant 100. As the inferiorridges 165 extend along their curvilinear path away from the insertionend 110, the inferior ridges 165 are interrupted to form a plurality ofinferior teeth 167. The inferior teeth 167 are disposed at theengagement end 115 and on the anterior and posterior sides of the axialbore 140. The superior and inferior ridges 160, 165 guide the insertionof the TLIF implant 100 under the compressive forces of the adjacentvertebral bodies, while the superior and inferior teeth 162, 167 assistin the primary fixation of the TLIF implant 100.

Referring to FIGS. 3, 4, and 6, one or more radiopaque markers 170, madefrom material capable of radiographical imaging, such as pins or beadsof stainless steel, titanium, tantalum, titanium-aluminum-niobium (TAN),or the like, are included in the TLIF implant 100 for enablingvisualization and controlling of the position of the TLIF implant 100during and after insertion into the disc space. In a first preferredembodiment, the markers 170 are elongated and include a first marker170A, a second marker 170B, and a third marker 170C. The first andsecond markers 170A, 170B are disposed in the cranial-caudal directionon either side of the lateral window 150 within the anterior wall 130 ofthe implant 100. The third marker 170C is disposed proximate theinsertion end 110, with a longitudinal axis thereof extending from theinsertion end 110 toward the axial bore 140.

The engagement end 115 is characterized by the absence of the walls 130extending fully between the superior and inferior surfaces 120, 125.That is, a slot 135 is formed at the engagement end 115 that extendscontinuously between and at least partially along the anterior andposterior walls 130. A post 180 is positioned within the slot 135, whichis spaced apart from the anterior and posterior walls 130 and extends atleast partially between the superior and inferior surfaces 120, 125 andserves as an instrument engagement feature. Adequate space is providedby the slot 135 for the engagement portion of an instrument 200 (FIG. 7)to engage the post 180. As shown in FIGS. 9 and 10, within the implant100, the walls 130 disposed between the axial bore 140 and the post 180include first and second mating surfaces 132, 134 facing the post 180between which an obtuse angle is formed for providing a pair ofmechanical stops to the range of allowable articulation of the implant100 with respect to the instrument 200. The first and second matingsurfaces 132, 134 are preferably linear surfaces, but may also be curvedor the like. Alternatively, stop pins or the like may be used to limitarticulation of the implant 100.

Referring now to FIGS. 9 and 10, in a first preferred embodiment, thepost 180 is polygonal in cross-section and includes nine exposed facets182 a-182 i arranged around an entire periphery thereof and extending inthe cranial-caudal direction between the superior and inferior surfaces120, 125. The facets 182 a-182 i are configured to enhance theengagement and interaction between the instrument 200 and the implant100 during the insertion of the implant 100. Preferably, seven of thefacets 182 a-182 f, 182 i are flat surfaces, while the remaining twofacets 182 g-182 h are curved surfaces. In an alternate embodiment, thepost 180 may include a different polygonal number of facets 182. In yetanother alternate embodiment, the post 180 can be cylindrical and thusinclude zero facets 182, and may include other features for governingthe articulation of the implant 100 with respect to the instrument 200during its insertion. For example, the post 180 can include dimples,teeth, surface texturing, grooves, or the like.

Referring now to FIGS. 1-5 and 7, the engagement end 115 of the superiorsurface 120 terminates in a superior corner 122, which includes superiorfirst and second flat segments 123, 124 originating near the post 180and converging at an angle disposed proximate the engagement end 115 ofthe implant 100. Similarly, the engagement end 115 of the inferiorsurface 125 terminates in an inferior corner 127, which include inferiorfirst and second flat segments 128, 129 originating near the post 180and converging terminating at an angle disposed proximate the engagementend 115 of the implant 100. The superior first flat segment 123 and theinferior first flat segment 128 are configured to be engagable by aportion of the instrument 200, as is described in detail below, toprovide a toggle-free connection, as are the superior second flatsegment 124 and the inferior second flat segment 129. The rims of boththe superior and inferior corner segments 122, 127 have a widthextending a short distance from the superior and inferior surfaces 120,125 toward the center of the implant 100. The surfaces of the rims arealso flat for enhancing the interaction between the instrument 200 andthe implant 100. The implant 100 can be formed from a variety ofbiocompatible materials, including but not limited to titanium,stainless steel, allograft bone, or polymers such aspolyaryletheretherketone (PEEK) and polyetherketoneketone (PEKK),titanfoam, porous PEEK, or the like.

Referring to FIGS. 7-8, an instrument 200 is provided that includes alongitudinal axis extending between a proximal end 201 and a distal end202. The instrument 200 includes an elongated cannulated outer member210 that surrounds an elongated inner member 250. The inner member 250is configured to be translatable with respect to the outer member 210along the longitudinal axis. Alternatively, the instrument 200 can beconfigured such that the outer member 210 is translatable with respectto the inner member 250 along the longitudinal axis to perform in thesame manner. The proximal end of the outer member 210 includes a handleportion (not shown) and an actuation mechanism (not shown) fortranslating the inner member 250 with respect to the outer member 210.The distal end of the outer member 210 includes an outer member firstarm 220 and an outer member second arm 240 that are separated by a gap230 that forms the distal portion of the cannula. The gap 230 includes apair of laterally-oriented surfaces 232 on either side of the cannuladisposed at the proximal end of the outer member first and second arms220, 240. The laterally-oriented surfaces 232 serve as a stop to theretraction of the inner member 250 with respect to the outer member 210.The interior surface of the first arm 220 includes an outer member firstarm interior linear taper 222 disposed distal to an outer member firstarm interior straight portion 224, while the interior surface of thesecond arm 240 includes an outer member second arm interior linear taper242 disposed distal to an outer member second arm interior straightportion 244. The first and second arm interior linear tapers 222, 242combine to form two wedging surfaces.

A laterally-extending superior exterior flat surface 215 of the outermember 210 is disposed between the distal ends of the outer member firstand second arms 220, 240 and the laterally-oriented surfaces 232.Similarly, a laterally-extending inferior exterior flat surface 216 ofthe outer member 210 is disposed between the distal ends of the outermember first and second arms 220, 240 and the laterally-orientedsurfaces 232. The laterally-extending superior exterior flat surface 215and the laterally-extending inferior exterior flat surface 216 areconfigured to serve as stops to prevent overarticulation of the implant100 by abutting the superior and inferior first flat segments 123, 128at one end of the articulation range and interacting with the superiorand inferior second flat segments 124, 129 at the other end of thearticulation range, as is described in detail below. Thelaterally-extending superior and inferior exterior flat surfaces 215,216 also abut against the superior and inferior first flat segments 123,128 of the implant 100, or against the superior and inferior second flatsegments 124, 129 of the implant 100, during a portion of the implantinsertion procedure.

The inner member 250 includes at its distal end a grasping portion 255an inner member first arm 260 and an inner member second arm 280separated by a split 270 that extends through the middle of the innermember 250 along the longitudinal axis from the grasping portion 255toward the proximal end. The interior surface of the grasping portion255 includes a plurality of engagement surfaces 257 that are configuredto complementarily match the polygonal cross sectional geometry of thepost 180 of the implant 100 and, thus, engage several of the pluralityof facets 182 a-182 i. In a first preferred embodiment, there are sevenengagement surfaces 257 a-257 g that are configured to engage seven ofthe nine facets 182 a-182 i of the post 180. Configured to interact withthe interior surfaces of the outer member first and second arms 220,240, the exterior surface of the inner member first arm 260 includes aninner member first arm exterior linear taper 262 disposed distal to aninner member first arm exterior straight portion 264, while the exteriorsurface of the inner member second arm 280 includes an inner membersecond arm exterior linear taper 282 disposed distal to an inner membersecond arm exterior straight portion 284. Disposed between the innermember first arm exterior linear taper 262 and the distal tip of theinner member first arm 260 is an inner member first arm second exteriorlinear taper 266.

Similarly, disposed between the inner member second arm exterior lineartaper 282 and the distal tip of the inner member second arm 280 is aninner member second arm second exterior linear taper 286. Further, aninner member first arm laterally-oriented flat surface 265 and an innermember second arm laterally-oriented flat surface 285 are formedproximal to and adjacent the inner member first arm exterior straightportion 264 and the inner member second arm exterior straight portion284, respectively, such that a pair of corners are formed therebetween,and such that the inner member first and second arm laterally-orientedflat surfaces 265, 285 face and abut with the laterally-orientedsurfaces 232.

Referring to FIG. 12, a trial implant 300 is provided that includesgeometry and surface features identical or similar to the implant 100and further includes a lateral hole 310 and a longitudinal hole 320 and,therefore, a complete description of the trial implant is omitted forconvenience only and is not limiting. The trial implant 300 is formedfrom a material that is visible under radiographic imaging, such astitanium, stainless steel, or the like. The lateral and longitudinalholes 310, 320, when viewed in conjunction with lateral and frontalX-rays, assist in the optimum positioning of the trial implant 300. Thelateral holes 310 allow the surgeon to center the trial implant 300 withrespect to the spinous processes of the vertebral bodies underfluoroscopy. The longitudinal hole 320 indicates whether the trialimplant 300 has turned, in which case the surgeon will know that moredisc material should preferably be removed. The lateral and longitudinalholes 310, 320 are shown as being generally circular or cylindrical inthe preferred embodiment, but are not so limited. The lateral andlongitudinal holes 310, 320 may have nearly any size and/or shape, suchas rectangular, square, arrow-shaped, and/or triangular that permitsvisualization of the location of the trial implant 300 under imaging. Inaddition, the trial implant 300 is not limited to including the lateraland longitudinal holes 310, 320 or any holes, as location of the trialimplant 300 may be visualized via markers or other features that areoptically or machine viewable.

In operation, and in continuing reference to FIGS. 1-12, a spinal discin need of repair or replacement is identified and an at least partialdiscectomy is performed, preferably via a unilateral transforaminalapproach. The trial implant 300 is inserted and removed using theinstrument 200 to gauge the appropriate size implant 100 for insertioninto the disc space. The insertion and manipulation of the trial implant300 using the instrument 200 is identical to the method of inserting andmanipulating the implant 100 using the instrument 200, as describedbelow. The lateral and longitudinal holes 310, 320 are viewed usinglateral and/or frontal X-rays to confirm the appropriate position of thetrial implant 300 within the disc space and an implant size is thenchosen.

Thus, the trial implant 300 is used for more than simply measuring theheight between the vertebral bodies. Since the trial implant 300articulates and is inserted to the same desired position as the finalimplant 100, the trial implant 300 may be used to determine whether thedesired position of the implant 100 is reachable, whether enough discmaterial has been removed, and the like.

The bone graft 190 is then inserted into the axial bore 140 and securedtherein via the surface features 145 (if not already preassembledthereto) and the implant 100 is then coupled to the instrument 200 bydistracting the outer member 210 with respect to the inner member 250via the manipulation of the actuation mechanism (not shown) such thatthe instrument 200 assumes an open configuration, as seen in FIGS. 7, 8,and 10C. The grasping portion 255 is then centered around the post 180and the inner member 250 is partially retracted with respect to theouter member 210 via the manipulation of the actuation mechanism,thereby forcing the pair of corners formed between the inner memberfirst and second arm exterior straight portions 264, 284 and the innermember first and second arm laterally-oriented flat surfaces 265, 285 toslidingly bear against the outer member first and second arm interiorlinear tapers 222, 242 until the inner member first and second armexterior straight portions 264, 284 come to bear against the outermember first and second arm interior straight portions 224, 244, whileproviding the gap 230 between the inner member first and second armlaterally-oriented flat surfaces 265, 285 and the laterally-orientedsurfaces 232. Consequently, the grasping portion 255 is collapsed aroundthe post 180 such that the engagement surfaces 257 a-g come into contactagainst the plurality of facets 182 a-i of the post 180 and such thatthe post 180 is provisionally captured by the grasping portion 255, asshown in FIG. 9C, with the inner member first arm second exterior lineartaper 286 bearing against the second linear surface 134.

In this provisionally locked configuration, the implant 100 is securedto the instrument but the post 180 is capable of rotation with respectto the grasping portion 255 but is prevented from exiting from thegrasping portion 255. Final locking of the grasping portion 255 aboutthe post 180, as shown in FIGS. 9A, 9B, 10A, and 10B, is achieved byfully retracting the inner member 250 with respect to the outer member210 via the continued manipulation of the actuation mechanism, therebyforcing the outer member first arm interior linear taper 222 and theouter member second arm interior linear taper 242 to come to bearagainst the inner member first arm exterior linear taper 262 and theinner member second arm exterior linear taper 282, respectively, therebyclosing the gap 230, and finally locking the implant 100 to theinstrument 200 while preventing any portions of the inner member firstand second arms 260, 280 from separating under force from one anotheracross the split 270 due to the contact between the outer member firstand second arm interior linear tapers 222, 242 and the inner memberfirst and second arm exterior linear tapers 262, 282. In this finallylocked configuration, the superior and inferior exterior flat surfaces215, 216 contact the superior and inferior first flat segments 123, 128,respectively, the gap 230 is closed, the inner member first arm secondexterior linear taper 286 still bears against the second linear surface134, and the post 180 is incapable of rotating with respect to thegrasping portion 255.

In the finally locked configuration, the handle portion of theinstrument 200 is grasped and the insertion end 110 of the implant isinserted into the transforaminal window created during the discectomyprocedure until the bullet nose 112 enters the disc space and begins todistract the adjacent vertebral bodies and the distal end of thesuperior and inferior ridges 160, 165 make contact with the inferiorsurface of the superior vertebral body and the superior surface of theinferior vertebral body, respectively. Gentle hammer blows or otherimpaction forces are administered to the proximal end 201 of theinstrument 200 to urge the implant 100 at least partially into the discspace. Toggling is prevented between the implant 100 and the instrument200 during the delivery of impaction forces due to the abutment of (1)the superior and inferior first flat segments 123, 128 with the superiorand inferior exterior flat surfaces 215, 216 and/or (2) the secondlinear surface 134 with the first arm second linear taper 286 and/or (3)the plurality of facets 182 a-i of the post 180 with the engagementsurface 257 a-f when the instrument 200 is in its finally lockedconfiguration with respect to the implant 100. Any of these abutmentsalone or in combination preferably prevent toggling between the implant100 and the instrument 200 in the finally locked configuration.

Once the impaction forces drive the implant 100 along a linear path to adesired position within the disc space, as seen in FIG. 11A, with theinstrument 200 finally locked to the implant 100, the inner member 250is advanced with respect to the outer member 210 such that theinstrument reassumes its provisionally locked configuration with respectto the implant 100, in which the implant 100 is coupled to theinstrument but the post 180 is capable of rotation with respect to thegrasping portion 255. At this point, additional gentle hammer blows orother impaction forces are administered to the proximal end of theinstrument 200 and the superior and inferior ridges 160, 165 contact theendplates of the vertebral bodies to promote turning of the implant 100and guide the path of insertion of the implant 100 as the insertion end110 progresses into the disc space. As the superior and inferior ridges160, 165 guide the implant 100 into the desired position within the discspace, the post 180 and, hence, the implant 100, rotates with respect tothe grasping portion 255 within a range restricted by the stops providedby the interaction between the inner member second arm second exteriorlinear taper 286 bearing against the second linear surface 134 (thestarting configuration of the insertion method) and the inner memberfirst arm second exterior linear taper 266 bearing against the firstlinear surface 132 (at maximum angulation).

Throughout the entirety of the insertion process, the angle of the shaftof the instrument 200 with respect to the disc space is maintainedconstant, as all of the action performed to articulate the implant 100is undertaken by the implant 100 itself as the gentle impaction forcesdrive the implant 100 into its desired final position guided by thesuperior and inferior ridges 160, 165, with no active turning of theimplant necessary. Upon contact between the inner member first armsecond exterior linear taper 266 and the first linear surface 132, theimplant 100 is at or near its desired final positioning interior to thedisc space. At this point, the implant 100 can be repositioned asnecessary by again finally locking the implant 100 to the instrument200, by retracting the inner member 250 distally with respect to theouter member 210, and manipulating the handle of the instrument 200until the optimum final positioning of the implant 100 is achieved withrespect to the disc space while viewing the position of the markers 170under fluoroscopic imaging. The arrangement of the markers 170 enables asingle radiographic image, e.g., a lateral image, to be used todetermine the precise position of the implant 100 with respect to thedisc space. The implant 100 is then released from the instrument 200 bymanipulating the actuation mechanism until the instrument 200 assumesits open configuration, as described previously, and the graspingportion 255 no longer contacts the post 180. The compression forcesbetween the vertebral endplates and the superior and inferior surfaces120, 125 maintain the implant 100 in place as the instrument 200 isremoved from the disc space and the patient's body.

The insertion and removal of the trial implant 300 may cause theformation of grooves in the adjacent endplates of the superior andinferior vertebral bodies due to the inclusion on the superior andinferior surfaces of the trial implant 300 of superior and inferiorridges that are identical to the superior and inferior ridges 160, 165of the implant 100. The formation of such grooves in the adjacentendplates of the superior and inferior vertebral bodies, while notrequired for insertion of the implant 100, may assist in easing theinsertion of the implant 100 using the instrument 200 via the guidedmating of the superior and inferior ridges 160, 165 with the groovesformed previously by the trial implant 300.

While embodiments of the present invention are described herein withrespect to an interbody spacer configured for insertion via atransforaminal path, a variety of implants may be utilized, such astotal disc replacements and nucleus replacement devices, by simplyconfiguring such implants to include an appropriately faceted post foran instrument engagement feature and, optionally, the stops andtoggle-free bearing surfaces described herein. As such, the implant 100is not limited to a banana or kidney bean shape, but may assume anygeometry that can be accommodated within the disc space. Further, arange of angular approaches to the disc space may be utilized where anelongated implant is desired to be manipulated or pivoted once it hasbeen delivered along a straight path into the disc space, such asposterior-lateral approaches, translateral, and direct lateralprocedures.

In an alternate embodiment, the non-toggling interface between theimplant 100 and the instrument 200 during the delivery of impactionforces that is provided by the interaction and abutment of the superiorand inferior first flat segments 123,128 with the laterally-extendingsuperior and inferior exterior flat surfaces 215, 216, as well as theinteraction and abutment of the superior and inferior second flatsegments 124, 129 with the laterally-extending superior and inferiorexterior flat surfaces 215, 216, can also be provided with non-linearabutment surfaces. As long as the surfaces mate or are able to abut oneanother when the instrument assumes its finally locked configuration, anon-toggling interface can be provided.

Similarly, the articulation stops that prevent overarticulation of theimplant 100 with respect to the instrument 200 that are embodied by thefirst and second linear surfaces 132, 134, and the range of articulationprovided by the obtuse angle disposed therebetween, can be provided by avariety of angles which can be tailored specifically to a desiredarticulation range for a given application, and therefore does notnecessarily need to be obtuse. Further, the first and second linearsurfaces 132, 134, as well as the inner member first and second armsecond exterior linear tapers 266, 286 that are abutted thereagainst,need not be linear surfaces. Rather, any mating abutment surfaces willsuffice between 132 and 266 and between 134 and 286 for the purposes oflimiting the articulation range. Further, an embodiment may beenvisioned in which the obtuse angle is removed between the first andsecond linear surfaces 132, 134 such that a single abutment surface isprovided that can limit the range of articulation by being abuttable byboth the first and second arm second exterior linear tapers 266, 286and, further, does not need to be linear as long as it provides a matingabutment surface to the geometry chosen for the first and second armsecond exterior linear tapers 266, 286.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications within the spirit and scope of thepresent invention as defined by the present description.

We claim:
 1. An intervertebral implant comprising: an insertion end andan opposing engagement end; first and second opposed main surfacesconfigured to contact respective first and second vertebral endplates,each of the first and second main surfaces defining an anterior end, anda posterior end, and each of the first and second main surfaces disposedbetween the insertion and engagement ends; an anterior wall disposedbetween the first and second main surfaces, the anterior wall disposedalong the anterior ends of the first and second main surfaces; aposterior wall disposed between the first and second main surfaces, theposterior wall disposed along the posterior ends of the first and secondmain surfaces, and the anterior wall and the posterior wall convergingat the insertion and engagement ends; a slot defined at the engagementend, the slot continuously disposed between and at least partially alongthe anterior and posterior walls; a post positioned within the slot, thepost spaced from at least one of the anterior or posterior walls, thepost at least partially disposed between the first and second mainsurfaces, and the post defining a plurality of exposed facets, theplurality of exposed facets being configured to engage complementaryfacets of an insertion instrument so as to rotatably couple the post tothe insertion instrument when the insertion instrument is engaged withthe post; and an abutment surface disposed within the slot and spacedfrom the post, the abutment surface having a first portion and a secondportion that is contiguous to the first portion, the first portion beingangularly offset from the second portion, the first and second portionsare configured to contact a surface of the insertion instrument when thepost is engaged with the insertion instrument so as to prevent rotationof the intervertebral implant about the post.
 2. The intervertebralimplant of claim 1, wherein each anterior end is generally concave andeach posterior end is generally convex.
 3. The intervertebral implant ofclaim 2, wherein each of the first and second main surfaces includes aplurality of curved parallel ridges protruding from the respectivesurface and extending from the insertion end to the engagement end, eachof the plurality of parallel ridges including a plurality of teeth. 4.The intervertebral implant of claim 1, wherein the anterior andposterior walls define a first height of the implant proximate theengagement end and a second height at the insertion end, the secondheight being less than the first height.
 5. An intervertebral implantconfigured to be inserted between a first and second vertebral endplatesalong an insertion direction, the intervertebral implant comprising: aninsertion end and an opposing engagement end spaced from the insertionend along the insertion direction when the implant is positioned betweenthe first and second vertebral endplates; first and second opposed mainsurfaces configured to contact the respective first and second vertebralendplates, each of the first and second main surfaces defining ananterior end, and a posterior end, first and second main surfacesdisposed between the insertion and engagement ends, each anterior endincluding a generally linear portion proximate the engagement end, eachanterior end including a generally concave portion, and each posteriorend including a generally linear portion proximate the engagement end,each posterior end including a generally convex portion, the generallylinear portion of the anterior end converging with the generally linearportion of the posterior end at the engagement end for each of the firstand second main surfaces; an anterior wall disposed between the firstand second main surfaces, and the anterior wall disposed along theanterior ends of the first and second main surfaces; a posterior walldisposed between the first and second main surfaces, and the posteriorwall disposed along the posterior ends of the first and second mainsurfaces, the anterior wall and the posterior wall converging at theinsertion and engagement ends; and a slot defined at the engagement end,the slot continuously disposed between and at least partially along theanterior and posterior walls; a post positioned within the slot, thepost spaced from at least one of the anterior or posterior walls, thepost disposed at least partially between the first and second mainsurfaces, the post being elongate along a central post axis that extendsthrough the first and second main surfaces and is perpendicular to theinsertion direction, the post defining a length that extends along thecentral post axis the post defining a plurality of exposed facetsconfigured such that the post is configured to be rotatably coupled toan insertion instrument, and a first facet of the plurality of facets isconfigured as a flat surface that extends along substantially anentirety of the length of the post.
 6. The intervertebral implant ofclaim 5, wherein each anterior end is generally concave and eachposterior end is generally convex.
 7. The intervertebral implant ofclaim 6, wherein each of the first and second main surfaces includes aplurality of curved parallel ridges protruding from the respectivesurface and extending from the insertion end to the engagement end, eachof the plurality of parallel ridges including a plurality of teeth. 8.The intervertebral implant of claim 5, wherein the anterior andposterior walls define a first height of the implant proximate theengagement end and a second height at the insertion end, the secondheight being less than the first height.
 9. An intervertebral implantcomprising: an insertion end and an opposing engagement end; first andsecond opposed main surfaces configured to contact respective first andsecond vertebral endplates, each of the first and second main surfacesdefining an anterior end, and a posterior end, each of the first andsecond main surfaces disposed between the insertion and engagement ends,each anterior end being generally concave, and each posterior end beinggenerally convex; an anterior wall disposed between the first and secondmain surfaces, the anterior wall disposed along the anterior ends of thefirst and second main surfaces; a posterior wall disposed between thefirst and second main surfaces, the posterior wall disposed along theposterior ends of the first and second main surfaces, the anterior walland the posterior wall converging at the insertion and engagement ends;and a slot defined at the engagement end, the slot continuously disposedbetween and at least partially along the anterior and posterior walls; apost positioned within the slot, the post spaced from the anterior andposterior walls, the post disposed at least partially between the firstand second main surfaces, the post defining a plurality of facets, thefacets disposed around an entire periphery of the post, the facetsconfigured such that the post is configured to be coupled to aninsertion instrument; a first abutment surface and a second abutmentsurface disposed within the slot, the first and second abutment surfacesspaced from the post, the first and second abutment surfaces beingsubstantially linear, the first abutment surface being angularly offsetfrom the second abutment surface, and the first and second abutmentsurfaces meet so as to define a non-zero angle, wherein the firstabutment surface is configured to contact a first surface of theinsertion instrument when the post is engaged with the insertioninstrument so as to prevent further rotation of the intervertebralimplant about the post in a first direction, and the second abutmentsurface configured to contact a second surface of the insertioninstrument when the post is engaged with the insertion instrument so asto prevent further rotation of the intervertebral implant about the postin a second direction that is opposite the first direction.
 10. Theintervertebral implant of claim 9, wherein each of the first and secondmain surfaces includes a plurality of curved parallel ridges protrudingfrom the respective surface and extending from the insertion end to theengagement end, each of the plurality of parallel ridges including aplurality of teeth.
 11. The intervertebral implant of claim 9, whereinthe anterior and posterior walls define a first height of the implantproximate the engagement end and a second height at the insertion end,the second height being less than the first height.
 12. Theintervertebral implant of claim 1, further comprising: an axial boredefined between the anterior and posterior ends, and the axial boredisposed between the first and second main surfaces; a plurality ofmarkers, at least one of the markers disposed between the first andsecond main surfaces within one of the anterior or posterior walls, atleast one other of the markers disposed generally transverse to the atleast one of the markers, and the at least one other of the markers iselongate in a direction from the insertion end toward the axial bore.13. The implant of claim 5 wherein the post is positioned within theslot so as to define a channel that extends between the anterior andposterior walls.
 14. An intervertebral implant configured to be insertedinto in an intervertebral space defined between a superior vertebra andan inferior vertebra, the intervertebral implant comprising: an implantbody that defines an insertion end, an opposed engagement end spacedfrom the insertion end along a longitudinal direction, a superiorsurface configured to face the superior vertebra, an inferior surfaceconfigured to face the inferior vertebra, the inferior surface beingspaced from the superior surface in a transverse direction that isperpendicular to the longitudinal direction, the implant body furtherdefining a first side surface, and a second side surface spaced from thefirst side surface along a lateral direction that is perpendicular tothe transverse direction and the longitudinal direction, the first andsecond side surfaces extending between the superior and inferiorsurface, the implant body further defining a slot that extends from thefirst side surface to the second side surface, an abutment surfacespaced from the engagement end, the abutment surface extending from thefirst side surface to the second side surface, and a post disposedwithin the slot and spaced from the abutment surface, the post beingelongate along a central post axis that is aligned with the transversedirection and perpendicular to the lateral and longitudinal directions,the post defining a plurality of exposed facets spaced from the centralpost axis and extending along the transverse direction, the plurality ofexposed facets being configured to engage complimentary facets of aninsertion instrument, wherein the abutment surface is configured as astop so as to prevent the insertion instrument from rotating about thecentral post axis.
 15. The intervertebral implant of claim 14, whereinthe abutment surface comprises a first portion and a second portion thatis contiguous to the first portion, the first portion being angularlyoffset from the second portion so as to define a non-zero angle.
 16. Theintervertebral implant of claim 14, wherein the post defines a lengththat is aligned with the transverse directions, wherein a first facet ofthe plurality of exposed facets is configured as a flat surface thatextends along substantially an entirety of the length of the post in thetransverse direction.
 17. The intervertebral implant of claim 14,further comprising a plurality of markers, at least one of the markersdisposed between the first and second main surfaces within one of theanterior or posterior walls, at least one other of the markers disposedgenerally transverse to the at least one of the markers.
 18. Theintervertebral implant of claim 14, further comprising at least onelateral window disposed in at least one of the first side surface andsecond side surface.